FAQ

  1. What is reJ?
  2. What do I need reJ for?
  3. How to run reJ?
  4. How do I use reJ?
What is reJ?

reJ is a graphical tool for manipulation and inspection of .class files of the Java platform.

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What do I need reJ for?

reJ probably shouldn't be a regular part of any development cycle. However, it can be very handy for various things.

  • Understanding the bytecode of the Java platform
  • Quick browsing through a binary distribution (for example, finding a version field of a class in a jar: Open the jar file with reJ, do a search for "version" and see the results)
  • Java-intelligent compare of classes / jar files / folders
  • Very small or temporary modifications to classes where there is no source available
  • Debugging classes where there is no source available

To get a more comprehensive idea, see the features of the latest version of reJ.

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How to run reJ?

Download the binary release of reJ: rej_vx.x_bin.zip from the Files section of the SourceForge project.

Unpack the zip archive. It contains an executable .jar file. If you wish to use the debugging funcionality of reJ, you will have to execute reJ manually, specifying the path to the tools.jar library of your JDK in the classpath, for example:

java -cp rej.jar;tools.jar net.sf.rej.gui.MainWindow

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How do I use reJ?

See the Hello World -tutorial to get a basic grasp of the GUI features.

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